A data storage device such as a magnetic, optical, or magneto-optical drive includes a rotating storage medium. For example, modem disc drives comprise one or more rigid discs that are coated with a magnetizable medium and mounted on the hub of a spindle motor for rotation at a constant high speed. Information is stored on the discs in a plurality of concentric circular tracks typically by an array of transducers (“heads”) mounted to a radial actuator for movement of the heads relative to the discs. Each of the concentric tracks is generally divided into a plurality of separately addressable data sectors.
The read/write transducer, e.g. a magnetoresistive read/write head, is used to transfer data between a desired track and an external environment. The heads are mounted via flexures at the ends of a plurality of actuator arms that project radially outward from the actuator body. The actuator body pivots about a shaft mounted to the disc drive housing at a position closely adjacent the outer extreme of the discs. The pivot shaft is parallel with the axis of rotation of the spindle motor and the discs, so that the heads move in a plane parallel with the surfaces of the discs.
The actuator arm is driven by a control signal fed to the voice coil motor (VCM) at the rear end of the actuator arm. A servo system is used to sense the position of the actuator and control the movement of the head above the disc using servo signals read from a disc surface in the disc drive. The servo system relies on servo information stored on the disc. The signals from this information generally indicate the present position of the head with respect to the disc, i.e., the current track position. The servo system uses the sensed information to maintain head position or determine how to optimally move the head to a new position centered above a desired track. The servo system then delivers a control signal to the VCM to rotate the actuator to position the head over a desired new track or maintain the position over the desired current track.
With time, as these components age and wear, problems may develop in the operation of the data storage device. However, field failure analysis of these problems is sometimes difficult. While various types of test can provide accurate analysis of the problems, they typically require the device to be removed from the host for testing. Removal of the device from the host for testing can result in additional problems. For example, removing the device from the host can cause new problems or failures. Additionally, using a different interface for failure analysis may mask some problems and cause other new problems. Finally, some problems may be host specific and testable only while the device is connected to the host.
Accordingly there is a need for a programmable self-test of the data storage device while the device is still connected to the host. The present invention provides a solution to this and other problems, and offers other advantages over the prior art.